If you filed an extension request that was accepted by the IRS they already have it; no need to submit it again. Or do you want it for some other reason?
Is this what you want?
I need a copy of my proof of extension to add to my submission for a refinance on my home since they require two years tax returns
@missinglink- Try returning to the thread where you posted your question--then scroll up and read the answer already there that tells you how to get what you need.